[Enhancement] Relax docusaurus dependencies and upgrade demo to v2.1.0 (#258)

* Remove yarn.lock from demo

* Relax docusaurus dependencies and upgrade to v2.1.0

* Relax docusaurus dependencies to begin at v2.0.1

Author: sserrata

demo/package.json

@@ -21,10 +21,10 @@
     "re-gen": "yarn clean-all && yarn gen-all"
   },
   "dependencies": {
-    "@docusaurus/core": "2.0.1",
-    "@docusaurus/plugin-google-gtag": "2.0.1",
-    "@docusaurus/plugin-pwa": "2.0.1",
-    "@docusaurus/preset-classic": "2.0.1",
+    "@docusaurus/core": "^2.0.1",
+    "@docusaurus/plugin-google-gtag": "^2.0.1",
+    "@docusaurus/plugin-pwa": "^2.0.1",
+    "@docusaurus/preset-classic": "^2.0.1",
     "@mdx-js/react": "^1.6.22",
     "clsx": "^1.1.1",
     "docusaurus-plugin-openapi-docs": "^1.1.11",